A Real-Time Hydrodynamic-Based Obstacle Avoidance System for Non-holonomic Mobile Robots with Curvature Constraints

Abstract

The harmonic potential field of an incompressible nonviscous fluid governed by the Laplace’s Equation has shown its potential for being beneficial to autonomous unmanned vehicles to generate smooth, natural-looking, and predictable paths for obstacle avoidance. The streamlines generated by the boundary value problem of the Laplace’s Equation have explicit, easily computable, or analytic vector fields as the path tangent or robot heading specification without the waypoints and higher order path characteristics. We implemented an obstacle avoidance approach with a focus on curvature constraint for a non-holonomic mobile robot regarded as a particle using curvature-constrained streamlines and streamline changing via pure pursuit. First, we use the potential flow field around a circle to derive three primitive curvature-constrained paths to avoid single obstacles. Furthermore, the pure pursuit controller is implemented to achieve a smooth transition between the streamline paths in the environment with multiple obstacles. In addition to comparative simulations, a proof of concept experiment implemented on a two-wheel driving mobile robot with range sensors validates the practical usefulness of the integrated system that is able to navigate smoothly and safely among multiple cylinder obstacles. The computational requirement of the obstacle avoidance system takes advantage of an a priori selection of fast computing primitive streamline paths, thus, making the system able to generate online a feasible path with a lower maximum curvature that does not violate the curvature constraint.

Special Feature on Advanced Mobile Robotics

“…It controls the relative speed of the pursuer with respect to the evader, depending on the distance between them. Kuo et al [57] showed an obstacle avoidance approach based on velocity potential function. They focused on curvature constraints for a mobile robot.…”

Obstacle Avoidance Control for Multisteering Mode of Multiaxle Wheeled Robot Based on Trajectory Prediction Strategy

“…By fully considering the nonholonomic constraints of mobile robot systems, Yuan et al [44] proposed a new quadrupole potential field method to plan collision-free trajectories. Kuo et al [45] implemented a kind of obstacle avoidance method focusing on curvature constraint for a nonholonomic mobile robot. It treated the robot as a particle and adopted the curvature constraint streamline and pure tracking streamline change method.…”

Low Cost Collision Avoidance System on Holonomic and Non- Holonomic Mobile Robots

“…Most of the obstacles are static which allows a mobile robot to detect obstacles with good accuracy. Researches focus on low cost vision sensors (Feng & Feng, 2017 and multi ultrasonic sensors (Chen et al, 2018, Kuo et al, 2018, Moussa et al, 2018. In a recent research study, low cost sensors including sonars, laser range finder and vision cameras are integrated (Pu et al, 2018) to generate efficient sensor network.…”